1. Field of the Invention
The present invention relates to a sheet accommodating apparatus, which is applied to a post-processing apparatus for post-processing or stapling sheets discharged from an image forming unit, especially for accommodating the sheets discharged from two image forming units, and to a complex image forming system which is equipped with the sheet accommodating apparatus.
2. Description of the Related Art
FIG. 12 is a diagram showing a prior art image forming system 100. This image forming system 100 is constructed by jointing a single post-processing apparatus 102 to a single image forming unit 101. The post-processing apparatus 102 once fetches and accommodates sheets discharged from the image forming unit 101, and post-processes and discharges the sheets. The post-processing apparatus is exemplified by that which has been disclosed in Japanese Examined Patent Publication JP-B2 8-9451(1996). This post-processing apparatus accommodates the sheets, as discharged from the single image forming unit, and staples them.
As the image forming unit, on the other hand, there have been known in the prior art a copying machine according to an electrophotographic method, a printer, a facsimile apparatus and a printing machine. At present, however, there has been generalized an image forming system in which there are combined a copying image forming unit and an image forming unit for forming an image with image signals coming from a computer or the like. In this complex image forming system, the individual image forming units are made independent of one another due to the image qualities, the image signals, the image forming costs and the image forming and processing speeds. The post-processing apparatus can be connected to each of the image forming units.
To the complex image forming system, on the other hand, there can be connected a multi-function sheet discharge apparatus which has been disclosed in Japanese Unexamined Patent Publication JP-A 8-217306(1996). This multi-function sheet discharge apparatus accommodates the individual sheets, as discharged from a plurality of image forming units, and discharges them in a predetermined sequence. To this complex image forming system, there can be further connected a post-processing apparatus through such multi-function sheet discharge apparatus.
In the complex image forming system, the individual image forming units are made independent of one another. On the other hand, the post-processing apparatus, as disclosed in JP-B2 8-9451(1996), is designed to fetch the sheets from the single image forming unit so that it cannot fetch the sheets from a plurality of image forming units. As a result, the post-processing apparatus is connected to each image forming unit so that the sheets from the individual image forming units are fetched and accommodated by the individual post-processing apparatus connected thereto. Thus, the post-processing apparatus has to be connected to each of the image forming units so that the sheet accommodation portion in the post-processing apparatus is complicated to enlarge the size of the apparatus. In order to post-process the sheets from the individual image forming units altogether, moreover, the sheets from the individual post-processing apparatus have to be further processes, and these works are troublesome for the operator.
To the complex image forming system, on the other hand, there is connected the multi-function sheet discharge apparatus which has been disclosed in JP-A 8-217306. In this case, too, the sheets from the individual image forming units of the complex image forming system are fetched and accommodated like before in the individual accommodation portions of the multi-function sheet discharge apparatus. As a result, the plural sheet accommodation portions are required to enlarge the size of the apparatus.